Stabilization and Structure Determination of the Recombinant C-Terminal Domain of Nephila Clavipes Dragline Silk

Spider silk, as simple as it may look, holds a secret which lies in the processing of the silk proteins from a highly concentrated soluble state to the insoluble fiber. The conserved C-terminal domain of MaSp1, the dragline silk main protein, appears to play a key role in the control of solubility and fiber formation initiated by changes in ionic composition, mechanical stimuli or pH variations along the secretory gland ducts. Therefore, the study of its structure is necessary to understand this remarkable molecular behaviour. We have established a purification protocol to prevent the aggregation of the recombinant Nephila clavipes MaSp1 C-terminal domain. We have also investigated the structure of the protein using solution nuclear magnetic resonance (NMR), dynamic light scattering (DLS) and fluorescence spectroscopy. NMR diffusion and DLS experiments provide information about the oligomerization and aggregation of the protein. Further NMR experiments with the doubly 13C/15N labelled protein will lead to the complete determination of the protein structure.